Wind power installation and method and apparatus for use in association therewith

ABSTRACT

The present invention concerns an apparatus for monitoring a wind power installation, with at least one sensor for detecting measurement values, and also a method of monitoring a wind power installation, in which: (i) a measurement value is detected with at least one sensor, (ii) the measurement value is converted into a signal representative of the measurement value, and (iii) the signal is stored and/or processed in accordance with a predetermined method. In one aspect, in order to provide an apparatus and a method which permit reliable detection of the loading on the pylon of the wind power installation, there is provided at least one sensor for detecting the loading on the pylon, the sensor being arranged in the region of the base of the pylon. In addition, the instantaneous loading on the wind power installation is ascertained from the signal representative of the measurement value ascertained by the sensor.

RELATED INFORMATION

The present invention concerns a wind power installation having amonitoring apparatus, with at least one sensor for detecting measurementvalues, and also a method of monitoring a wind power installation, inwhich a) a measurement value is detected with at least one sensor, b)said measurement value is converted into a signal representative of themeasurement value, and c) the signal is stored and/or processed inaccordance with a predetermined method.

Such apparatuses and methods are known in the state of the art. Thejournal ‘Erneuerbare Energien’ [‘Renewable Energies’], issue July 2000,page 38, which appeared at SunMedia Verlags- und Kongressgesellschaftfür Erneuerbare Energien mbH Hannover, in an article entitled ‘Knacktder Rotor den Turm’ [‘The rotor roughs up the pylon’], mentionsoscillation monitoring by means of acceleration measurement.

Issue No May 2000 of that journal, in paragraph 2 on page 37 thereof,describes that the oscillation monitors which are nowadays offered byseveral manufacturers involve acceleration pickups. Also describedtherein is a method in which dangerous frequencies are deliberately andspecifically amplified by means of an electronic system.

That state of the art permits detection of oscillations of the head ofthe pylon in certain frequency ranges. Those oscillations form a part ofthe loadings on the pylon. In that respect the pylon is designed for apredetermined total of loadings during its intended service life of forexample 20 years.

Each loading makes a contribution to material fatigue. It is thereforeeasy to understand that, at locations with a large number of highloadings, fatigue progresses more quickly than at locations with few andlow loadings.

This therefore involves a differing ‘mechanical’ age, with an assumedidentical age of the pylons in terms of time. In that respect, it canhappen that, when reaching its age limit in terms of time of 20 years,the pylon which has been subjected to lower levels of loading hasmechanically only experienced a loading which, in regard to the designthereof, was already intended after 15 years, so that the pylon cancertainly still remain in operation. It will be appreciated that thereverse situation is also conceivable, in which a pylon has alreadyreached a mechanical age of 20 years, after just 15 years.

With the previous arrangements, the mechanical service age of a pyloncan still not be adequately detected, so that ultimately it is onlypossible to arrive at vague estimates about the service life of a pylonand thus one of the most important parts of the wind power installation.

SUMMARY OF THE INVENTION

An object of one aspect of the invention is to provide an apparatus anda method which permits reliable detection of the loading on the windpower installation and a reliable estimate of important parts of thewind power installation.

In one aspect, the invention is based on the realization that all loadswhich occur at a wind power installation act on the pylon of theinstallation. If the base of the pylon has experienced half the loadcollective, the other components such as blades, machine carrier, headof the pylon, pylon etc, can scarcely have experienced a significantlyhigher proportion of the load collective.

Ultimately, the load at the base of the pylon cannot correspond to asituation involving a wind speed of for example 4 m/s while the load atother components corresponds for example to a wind speed of 8 m/s.Therefore, detecting the loading on the pylon makes it possible toarrive at a conclusion about the loadings to which the wind powerinstallation is overall exposed at its site.

As, in a simplification, the wind power installation can be viewed as abar which is gripped at one end, it is possible to detect the sum of allloads acting on the wind power installation, at the base of the pylon.Arranging at least one sensor in the region of the base of the pylontherefore permits reliable detection of the loading on the wind powerinstallation. At the same time it is possible to reach the sensorwithout aids and without involving a high degree of expenditure andcomplication.

In a preferred embodiment of the invention detection of the loading iseffected by a sensor based on a RSG (resistance strain gauge). Theloading can be reliably detected by means of such a sensor, with anadequate degree of accuracy, using tried and tested technology.

The measurement values detected by the resistance strain gauge areparticularly preferably converted into analog or digital electricalsignals which are representative of the measurement values. Thosesignals can be transmitted and subjected to further processing in asimple manner.

Such further processing can be a comparison with a limit value in orderfor example to be able to recognise load maxima or to ascertain whenpredeterminable load limits are reached or exceeded. In addition themeasurement values can be cumulated and stored for subsequent processingor evaluation.

It will be appreciated that the result of the cumulation can also inturn be compared to a predeterminable limit value. In that way it ispossible to consider the loading on the installation in relation to thedesign loads and thus to implement an estimate of the mechanical serviceage of the installation.

In addition the method as referred to in the opening part of thisspecification is developed in such a way that the instantaneous loadingon the wind power installation is ascertained from the signal from thesensor. As, in extensive measurements on the prototype of a wind powerinstallation, the correlation of the load situations at variouscomponents of the wind power installation is also ascertained, data areavailable, which make it possible to draw a conclusion, from the load atthe base of the pylon, about the load on the other components. By virtueof cumulation of all the ascertained loadings it is possible toascertain the overall loading on the wind power installation and thusits mechanical service age.

By virtue of a correlation of the instantaneous loading with theinstantaneous wind, it is possible to check whether the ascertainedinstantaneous loading on the wind power installation corresponds to anapproximately expected order of magnitude. It is possible in that mannerto monitor satisfactory functioning of the apparatus according to theinvention.

The measured loading data can also be subjected to further processing ina control apparatus of the wind power installation in such a way that,when an overload occurs, the control apparatus implements measures whichresult in a reduction in the loading. Such a reduction in loading can beeffected for example by adjustment of the rotor blades (out of the wind)or also by a reduction in the speed of rotation of the rotor of the windpower installation. In addition the entire rotor of the wind powerinstallation could be rotated out of the wind through a given angle, toreduce the loading.

The method according to one aspect of the invention results in adetailing of the load total which has been experienced to date by thewind power installation, in relation to the design loads. Thatrelationship, like also individual measurement values and/or thecumulated loading, can be stored and/or processed in the installation.In addition those data can be for example regularly transmitted to aremote location such as a remote monitoring system, or called uptherefrom.

An embodiment of the invention by way of example thereof is describedhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified view of a wind power installation,

FIG. 2 shows an arrangement of sensors, and

FIG. 3 shows a flow chart of the method according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a pylon 10 of a wind power installation, which is connectedto a foundation 12. Arranged at the head of the pylon 10 is a pod 14which has a rotor which rotor blades 16. In this Figure the arrowdenotes the direction of the wind.

The wind rotates on the one hand the rotor and therewith thesubsequently mechanically coupled part of the wind power installation inorder to generate electrical energy. At the same time however on the onehand the pylon 10 is subjected to the effect of the pressure of the windand on the other hand the pod 14 with the rotor is deflected in thedirection of the wind. As a result, a bending moment occurs at the pylon10 which is gripped at one end, over the lever arm of the length of thepylon, at the foundation 12.

The effect of the force acting on the head of the pylon produces a forcepattern over the entire length of the pylon so that the alternatingloads or oscillations cause a corresponding material fatigue effect.

FIG. 2 shows an arrangement of two sensors 20 in the region of the baseof the pylon. Those sensors 20 can operate for example on the basis ofRSGs (resistance strain gauges) and detect the stress at the base of thepylon. That stress permits a quite accurate conclusion to be drawn aboutthe overall stress on the wind power installation. Instead of thearrangement of only two sensors it may also be advantageous under somecircumstances to arrange a plurality of sensors distributed around theperiphery of the base of the pylon in order in that way to affordsensors for a plurality of main wind directions, in such a fashion thatthe sensors can ascertain the respective maximum tensile/compressionloadings which occur on the base of the pylon.

In addition the signals/data ascertained with the sensors can besubjected to further processing in a control apparatus of the wind powerinstallation (not shown) in such a way that, when predetermined maximumvalues are exceeded once, a plurality of times or in a time-wise manner,the overall loading on the wind power installation is reduced, by aprocedure such that for example the speed of rotation of the rotor ofthe wind power installation is reduced by means of the control systemand/or the individual rotor blades are rotated out of the wind through agiven angle, thereby reducing the loading which acts due to the rotor orthe effect of the wind acting thereon.

The second device 40 can detect the electrical signals and evaluate orprocess them. The measurement values can be compared for example to afirst limit value which marks a predetermined load limit. If themeasurement value reaches or exceeds that first limit value, a signalcan be triggered, which displays precisely that.

If the limit value, that is to say in the present example a load limit,is reached/exceeded in that way repeatedly, that makes it possible toconclude that there is a systematic deviation from load assumptionswhich have been previously made. Thereupon it is possible to restrictthe cause thereof, for example incorrect control of the wind powerinstallation or an extreme situation which is dependent on the site ofthe installation, so that it is possible to produce a remedy in thatrespect.

Mechanical ageing of the pylon can be constantly monitored by continuedcumulative recording and continuous comparison with the design loads.

Storage of the load data also has the advantage that, in the event ofdamage possibly occurring to the pylon of the wind power installation,it is more easily possible to obtain proof of whether given overloadphases have occurred and whether the maximum loadings occurring werecomplied with.

Finally, it is also advantageous if the measured load data of a windpower installation are acquired centrally and, in the event that themeasured load data frequently or constantly exceed a given maximumvalue, measures can be implemented on the part of the operator in goodtime, to prevent premature mechanical ageing of the pylon. Such ameasure for example may also involve strengthening certain elements ofthe wind power installation, including for example the pylon.

Instead of a resistance strain gauge, for detecting the loading it isalso possible to use any other device by means of which tensile forcesand/or compression forces and/or torsion forces and/or oscillations orthe amplitudes thereof in the pylon and in particular the top of thepylon of a wind power installation can be detected.

FIG. 3 shows a flow chart of a method according to the invention. Theprocedure begins with the step 50 and the measurement value is detectedin step 51. In step 52 the detected measurement value is compared to afirst limit value. If the measurement value exceeds that first limitvalue, it is precisely this that is indicated in step 53. If themeasurement value does not exceed the first limit value the proceduremisses out step 53.

In step 54 the measurement values are cumulated so that the overallloading experienced by the wind power installation to date isascertained. That overall loading is related to the design loads in step55. It is possible to read therefrom the mechanical service age, that isto say the load collective already experienced by the wind powerinstallation, in relation to the design load collective. Thatrelationship is represented in step 56 before the procedure terminateswith step 57.

The representation can be effected for example after data transmissionin a central remote monitoring station or at the operator of the windpower installation and can be in the form of a bar chart, a pie chart orany other suitable form of representation.

1. A wind power installation to generate electrical energy in response to wind, the wind power installation comprising: a pylon having a base; a rotor, supported by the pylon, to rotate in response to wind, wherein in response to the rotation of the rotor, the wind power installation generates electrical energy; at least one load sensor to sense loading in a region of the base of the pylon and to provide data representative of the loading; and a control device to receive the data representative of the loading and to control the wind power installation to reduce loading on the wind power installation if the data exceeds a predetermined value.
 2. The wind power installation of claim 1 wherein the load sensor includes at least one sensor disposed in the region of the base.
 3. The wind power installation of claim 1 wherein the load sensor includes a plurality of sensors distributed around the periphery of the base of the pylon.
 4. The wind power installation of claim 1 wherein the control device controls the wind power installation to reduce a rotational speed of the rotor to reduce the loading on the wind power installation.
 5. The wind power installation of claim 1 wherein the control device controls the wind power installation to rotate the rotor to reduce the loading on the wind power installation.
 6. The wind power installation of claim 1 wherein the rotor includes rotor blades and the control device controls the wind power installation to adjust the rotor blades to reduce the loading on the wind power installation.
 7. The wind power installation of claim 1 wherein the base of the pylon is connected to a foundation.
 8. The wind power installation of claim 1 wherein the control apparatus controls the wind power installation to reduce loading on the wind power installation if the data exceeds a predetermined value a plurality of times.
 9. The wind power installation of claim 1 wherein the control apparatus controls the wind power installation to reduce loading on the wind power installation if the data exceeds a predetermined value over a predetermined period of time.
 10. The wind power installation of claim 1 wherein the load sensor includes a sensor based on resistance strain gauges.
 11. The wind power installation of claim 1 wherein the data representative of the loading comprises analog or digital electrical signals and the load sensor includes a first device to convert the sensed loading into the analog or digital electrical signals.
 12. The wind power installation of claim 11 wherein the control device compares loading values represented by the analog or digital signals to at least one predetermined first limit value and wherein the installation further includes a device to display when the predetermined first limit value is reached or exceeded.
 13. The wind power installation of claim 11 further comprising a device to store loading values represented by the electrical signals.
 14. The wind power installation of claim 11 further comprising a device to cumulate loading values represented by the electrical signals.
 15. The wind power installation of claim 14 further comprising a device to transmit signals that represent the cumulated loading values.
 16. The wind power Installation of claim 14 further comprising a device to transmit signals that represent a relationship of the cumulated loading values with a predetermined second limit value.
 17. The wind power installation of claim 11 further comprising a device to transmit signals that represent individual loading values.
 18. A method of controlling a wind power installation that generates electrical energy in response to wind, the installation including a pylon and a rotor supported by the pylon, the pylon including a base, the method comprising: generating electrical energy in response to wind by rotation of the rotor; sensing loading in a region of the base of the pylon; providing data representative of the loading; and controlling the wind power installation to reduce loading on the wind power installation if the data exceeds a predetermined value.
 19. The method of claim 18 wherein sensing loading in a region of the base of the pylon includes providing at least one sensor in the region of the base.
 20. The method of claim 18 further comprising cumulating loading values represented by the electrical signals.
 21. A method of monitoring a wind power installation, the method comprising: generating electrical energy in response to wind by detecting rotation of a rotor, detecting loading on the wind power installation by means of a measurement value data pickup that provides measurement value data representative thereof; and processing the measurement value data to determine the instantaneous loading on the overall wind power installation.
 22. The method of claim 21 further comprising cumulating instantaneous loadings.
 23. The method of claim 22 further comprising relating the cumulated measurement values to a predetermined second limit value.
 24. The method of claim 23 further comprising providing a representation of the relationship between the cumulated measurement values and the second limit value.
 25. The method of claim 21 further comprising correlating instantaneous loadings with instantaneously measured wind.
 26. The method of claim 21 further comprising comparing the measurement value to a predetermined first limit value and displaying attainment or exceeding of the first limit value.
 27. The method of claim 21 wherein the wind power installation includes a pylon and a rotor supported by the pylon, the pylon having a base, and wherein detecting loading comprises detecting loading in a region of the base of the pylon.
 28. The method of claim 21 further comprising storing the measurement value data. 